1. Field of the Invention
The present invention relates to a system for filling a tank, in particular a fuel tank.
The fill pipes present in fuel tanks, in particular the tanks aboard motor vehicles, are sealed during normal use of the tank, outside the filling periods. Sealing is generally performed by means of a cap that is introduced into the upper part of the pipe while transmitting a rotational movement thereto in order to close the pipe in a liquid-tight and gas-tight manner.
2. Description of the Related Art
The operations of removing the cap before filling the tank, of replacing this cap and of closing the pipe after filling are most of the time carried out manually by the user. When the tank filling is finished, it may sometimes be forgotten to replace the cap and this then gives rise to the loss of this cap and to the pipe remaining open to the atmosphere for an indeterminate time. During this period, loss of liqud fuel occurs and vapours escape into the atmosphere.
For the purpose of preventing loss of the cap and contamination of the atmosphere which results therefrom, sealing systems integrated to the fill pipe, often called “capless” systems, have been proposed, replacing the traditional cap. Thus, for example, Application FR 2 861 655 in the name of the Applicant describes a pipe system with a chamber, arranged in which is a stopper that can be moved between an open position, in which the opening of the passage is aligned with the inlet and outlet openings of the chamber, and a closed position, in which the outlet opening is sealed. Such a pipe system has the advantage that the stopper is integrated into the pipe head and cannot be lost or forgotten. Moreover, an automatic opening and closing of the pipe head by introduction and withdrawal of a filling nozzle enables the task of the user to be made easier.
Furthermore, with a view to preventing the release of gases and liquids to the atmosphere while filling the tank, systems with a mechanical seal have been developed: see, for example, Application WO 02/072377 in the name of the Applicant. Although very effective, these systems generally involve a cost premium (linked in particular to the relatively complicated geometry of the seal) and will only be truly commercialized when they are imposed by legislation relating to the environment. The systems marketed currently indeed do not generally comprise such a seal and the fuel vapours generated during filling are either completely discharged to the environment, or partly recirculated in the fill head.
One drawback of such systems (without a mechanical seal) is however the possibility of discharge of liquid fuel during the filling phase, in particular at the end of the filling phase. Specifically, the pressure increase in the fill pipe during the filling phase may cause a discharge of liquid fuel in the direction of the user. The discharged fuel may be projected in the direction of the user especially because the head and fill pipe generally have a cross section larger than the diameter of the nozzle, which therefore allows the liquid to be discharged. This phenomenon, often called “spit-back” must of course be prevented to protect the user and the environment.